Stick and slip actuators: design, control, performances and applications

This paper describes stick and slip actuators, which can be included into the family of inertial drives. We propose several configurations and a modeling of these actuators. Stick and slip actuators present the advantage of allowing long displacements (several centimeters or even more) at high speed (several mm/s) with ultrahigh resolution (<5 mn). Moreover, they are simple, compact and have high stiffness. They are therefore well adapted to challenging applications such as micromanipulation. Long displacements are obtained by stepping motion (stepping mode), each step being typically 400 mm, while fine displacements with high resolution are made possible by a scanning-mode. A simple controller, combining stepping- and scanning-modes, has been designed. The excellent performance of a 1-degree-of-freedom (1-DOF) actuator is demonstrated. An innovative concept, the so called "monolithic piezoceramics flexible structures" allowing to design extremely simple micromanipulators, is also reported. Four prototypes are presented: a 1-DOF actuator, a 6-DOF platform and two 3-DOF mobile microrobots. The authors also describe briefly four applications where stick and slip actuators have been used successfully, namely: a sample holder for AFM (tilt), a micro-EDM machine, a microassembly system and a micro-telemanipulation system for biological specimens.